1. Field of the Invention
The present invention relates to a regulation circuit for a Color Display Tube (CDT), and, more particularly, to an apparatus and method for generating a high-voltage regulation signal capable of protecting components in a regulation circuit.
2. Description of the Related Art
Images on a bright area of a display screen sometimes appear as being expanded, and images on a dark area of the display screen sometimes appear as being contracted. This situation occurs because of a poor high-voltage regulation. Generally, image displays include a regulation circuit for controlling such a high-voltage regulation which has a direct influence on picture quality.
FIG. 1 is a block diagram of a regulation circuit used in a conventional Color Display Tube (CDT). The regulation circuit comprises an oscillation circuit 100, a Pulse Width Modulation (PWM) generator 110, a switching unit 120, a transformer 130, an error detector 140, and a feedback unit 150.
The oscillation circuit 100 generates an oscillation clock pulse. The PWM generator 110 generates and outputs a PWM control signal for controlling a high-voltage regulation using the oscillation clock pulse. The switching unit 120 outputs a signal switched according to the PWM control signal output from the PWM generator 110.
The transformer 130 generates and outputs a high-voltage regulation signal at a secondary side, using an output signal from the switching unit 120 as a primary-side voltage. The transformer 130 supplies the high-voltage regulation signal via a secondary-side output to the CDT, and simultaneously supplies a feedback voltage, proportional to the high-voltage regulation signal, to the PWM generator 110 via the feedback unit 150.
The error detector 140 detects an error using the signal output from the switching unit 120. When an error is detected, the error detector 140 notifies the PWM generator 110 of the error to enable the PWM generator 110 to stop outputting the PWM signal.
However, in the conventional regulation circuit, an error is detected after an excessive current due to the error already flows to the switching unit 120, and then the voltage signal input to the switching unit 120 is controlled. Therefore, components constituting the switching unit 120 can be damaged due to the excessive current. Such a damage of the switching unit adversely affects the control of the regulation voltage, thereby resulting in deterioration of picture quality of the CDT. Furthermore, the components constituting the switching unit 120 must be frequently replaced, resulting in an increase in cost of the whole system.